δ‐CsPbI3 Intermediate Phase Growth Assisted Sequential Deposition Boosts Stable and High‐Efficiency Triple Cation Perovskite Solar Cells

Cs/FA/MA triple cation perovskite films have been well developed in the antisolvent dripping method, attributable to its outstanding photovoltaic and stability performances. However, a facile and effective strategy is still lacking for fabricating high‐quality large‐grain triple cation perovskite films via sequential deposition method a, which is one of the key technologies for high efficiency perovskite solar cells. To address this issue, a δ‐CsPbI₃ intermediate phase growth (CsPbI₃‐IPG) assisted sequential deposition method is demonstrated for the first time. The approach not only achieves incorporation of controllable cesium into (FAPbI₃)_1–x(MAPbBr₃)_x perovskite, but also enlarges the perovskite grains, manipulates the crystallization, modulates the bandgap, and improves the stability of final perovskite films. The photovoltaic performances of the devices based on these Cs/FA/MA perovskite films with various amounts of the δ‐CsPbI₃ intermediate phase are investigated systematically. Benefiting from moderate cesium incorporation and intermediate phase‐assisted grain growth, the optimized Cs/FA/MA perovskite solar cells exhibit a significantly improved power conversion efficiency and operational stability of unencapsulated devices. This facile strategy provides new insights into the compositional engineering of triple or quadruple cation perovskite materials with enlarged grains and superior stability via a sequential deposition method.     

Short‐Chain Ligand‐Passivated Stable α‐CsPbI3 Quantum Dot for All‐Inorganic Perovskite Solar Cells

Cubic phase CsPbI₃ (α‐CsPbI₃) perovskite quantum dots (QDs) have received extensive attention due to their all‐inorganic composition and suitable band gap (1.73 eV). However, α‐CsPbI₃ QDs might convert to δ‐CsPbI₃ (orthorhombic phase with indirect band gap of 2.82 eV) due to easy loss of surface ligands. In addition, commonly used long‐chain ligands (oleic acid, OA, and oleylamine, OLA) hinder efficient charge transport in optoelectronic devices. In order to relieve these drawbacks, OA, OLA, octanoic acid, and octylamine are used as capping ligands for synthesizing high‐quality α‐CsPbI₃ QDs. The results indicate that these QDs exhibit excellent optical properties and long‐term stability compared to QDs capped only with OA and OLA. Moreover, QDs with shorter ligands exhibit an enhanced charge transport rate, which improves the power conversion efficiency of photovoltaic devices from 7.76% to 11.87%.     

Dual‐Phase All‐Inorganic Cesium Halide Perovskites for Conducting‐Bridge Memory‐Based Artificial Synapses

Neuromorphic computing, which mimics biological neural networks, can overcome the high‐power and large‐throughput problems of current von Neumann computing. Two‐terminal memristors are regarded as promising candidates for artificial synapses, which are the fundamental functional units of neuromorphic computing systems. All‐inorganic CsPbI₃ perovskite‐based memristors are feasible to use in resistive switching memory and artificial synapses due to their fast ion migration. However, the ideal perovskite phase α‐CsPbI₃ is structurally unstable at ambient temperature and rapidly degrades to a non‐perovskite δ‐CsPbI₃ phase. Here, dual‐phase (Cs₃Bi₂I₉)_0.4?(CsPbI₃)_0.6 is successfully fabricated to achieve improved air stability and surface morphology compared to each single phase. Notably, the Ag/polymethylmethacrylate/(Cs₃Bi₂I₉)_0.4?(CsPbI₃)_0.6/Pt device exhibits non‐volatile memory functions with an endurance of ≈10³ cycles and retention of ≈10⁴ s with low operation voltages. Moreover, the device successfully emulates synaptic behavior such as long‐term potentiation/depression and spike timing/width‐dependent plasticity. This study will contribute to improving the structural and mechanical stability of all‐inorganic halide perovskites (IHPs) via the formation of dual phase. In addition, it proves the great potential of IHPs for use in low‐power non‐volatile memory devices and electronic synapses.     

Stable α‐CsPbI3 Perovskite Nanowire Arrays with Preferential Crystallographic Orientation for Highly Sensitive Photodetectors

All‐inorganic metal‐halide perovskites CsPbX₃ (X = Cl, Br, I) exhibit higher stability than their organic–inorganic hybrid counterparts, but the thermodynamically instable perovskite α phase at room temperature of CsPbI₃ restricts the practical optoelectronic applications. Although the stabilization of α‐CsPbI₃ polycrystalline thin films is extensively studied, the creation of highly crystalline micro/nanostructures of α‐CsPbI₃ with large grain size and suppressed grain boundary remains challenging, which impedes the implementations of α‐CsPbI₃ for lateral devices, such as photoconductor‐type photodetectors. In this work, stable α‐CsPbI₃ perovskite nanowire arrays are demonstrated with large grain size, high crystallinity, regulated alignment, and position by controlling the dewetting dynamics of precursor solution on an asymmetric‐wettability topographical template. The correlation between the higher photoluminescence (PL) intensity and longer PL lifetime indicates the nanowires exhibit stable α phase and suppressed trap density. The preferential (100) orientation is characterized by discrete diffraction spots in grazing incidence wide‐angle scattering patterns, suggesting the long‐range crystallographic order of these nanowires. Based on these high‐quality nanowire arrays, highly sensitive photodetectors are realized with a responsivity of 1294 A W^?1 and long‐term stability with 90% performance retention after 30‐day ambient storage.     

Air‐Stable Cesium Lead Iodide Perovskite for Ultra‐Low Operating Voltage Resistive Switching

CsPbX₃ (X = halide, Cl, Br, or I) all‐inorganic halide perovskites (IHPs) are regarded as promising functional materials because of their tunable optoelectronic characteristics and superior stability to organic–inorganic hybrid halide perovskites. Herein, nonvolatile resistive switching (RS) memory devices based on all‐inorganic CsPbI₃ perovskite are reported. An air‐stable CsPbI₃ perovskite film with a thickness of only 200 nm is successfully synthesized on a platinum‐coated silicon substrate using low temperature all‐solution process. The RS memory devices of Ag/polymethylmethacrylate (PMMA)/CsPbI₃/Pt/Ti/SiO₂/Si structure exhibit reproducible and reliable bipolar switching characteristics with an ultralow operating voltage (<+0.2 V), high on/off ratio (>10⁶), reversible RS by pulse voltage operation (pulse duration < 1 ms), and multilevel data storage. The mechanical flexibility of the CsPbI₃ perovskite RS memory device on a flexible substrate is also successfully confirmed. With analyzing the influence of phase transition in CsPbI₃ on RS characteristics, a mechanism involving conducting filaments formed by metal cation migration is proposed to explain the RS behavior of the memory device. This study will contribute to the understanding of the intrinsic characteristics of IHPs for low‐voltage resistive switching and demonstrate the huge potential of them for use in low‐power consumption nonvolatile memory devices on next‐generation computing systems.     

NbF5: A Novel α‐Phase Stabilizer for FA‐Based Perovskite Solar Cells with High Efficiency

The HC(NH₂)₂⁺(FA⁺) is a well‐known substitute to CH₃NH₃⁺(MA⁺) for its capability to extend light utilization for improved power conversion efficiency for perovskite solar cells; unfortunately, the dark cubic phase (α‐phase) can easily transition to the yellow orthorhombic phase (δ‐phase) at room temperature, an issue that prevents its commercial application. In this report, an inorganic material (NbF₅) is developed to stabilize the desired α‐phase perovskite material by incorporating NbF₅ additive into the perovskite films. It is found that the NbF₅ additive effectively suppresses the formation of the yellow δ‐phase in the perovskite synthesis and aging process, thus enhancing the humidity and light‐soaking stability of the perovskite film. As a result, the perovskite solar cells with the NbF₅ additive exhibit improved air stability by tenfold, retaining nearly 80% of their initial efficiency after aging in air for 50 d. In addition, under full‐sun AM 1.5 G illumination of a xenon lamp without any UV‐reduction, the perovskite solar cells with the NbF₅ additive also show fivefold improved illumination stability than the control devices without NbF₅.     

Precursor Engineering for All‐Inorganic CsPbI2Br Perovskite Solar Cells with 14.78% Efficiency

The optoelectronic properties of perovskite films are closely related to the film quality, so depositing dense, uniform, and stable perovskite films is crucial for fabricating high‐performance perovskite solar cells (PSCs). CsPbI₂Br perovskite, prized for its superb stability toward light soaking and thermal aging, has received a great deal of attention recently. However, the air instability and poor performance of CsPbI₂Br PSCs are hindering its further progress. Here, an approach is reported for depositing high‐quality CsPbI₂Br films via the Lewis base adducts PbI₂(DMSO) and PbBr₂(DMSO) as precursors to slow the crystallization of the perovskite film. This process produces CsPbI₂Br films with large‐scale crystalline grains, flat surfaces, low defects, and long carrier lifetimes. More interestingly, PbI₂(DMSO) and PbBr₂(DMSO) adducts could significantly improve the stability of CsPbI₂Br films in air. Using films prepared by this technique, a power conversion efficiency (PCE) of 14.78% is obtained in CsPbI₂Br PSCs, which is the highest PCE value reported for CsPbI₂Br‐based PSCs to date. In addition, the PSCs based on DMSO adducts show an extended operational lifetime in air. These excellent performances indicate that preparing high‐quality inorganic perovskite films by using DMSO adducts will be a potential method for improving the performance of other inorganic PSCs.     

Ultrafast Responsive Non‐Volatile Flash Photomemory via Spatially Addressable Perovskite/Block Copolymer Composite Film

The exotic photophysical properties of organic–inorganic hybrid perovskite with long exciton lifetimes and small binding energy have appeared as promising front‐runners for next‐generation non‐volatile flash photomemory. However, the long photo‐programming time of photomemory limits its application on light‐fidelity (Li‐Fi), which requires high storage capacity and short programming times. Herein, the spatially addressable perovskite in polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO)/perovskite composite film as an photoactive floating gate is demonstrated to elucidate the effect of morphology on the photo‐responsive characteristics of photomemory. The chelation between lead ion and PEO segment promotes the anti‐solvent functionalities of the perovskite/PS‐b‐PEO composite film, thus allowing the solution‐processable poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) to act as the active channel. Through manipulating the interfacial area between perovskite and P3HT, fast photo‐induced charge transfer rate of 0.056 ns^?1, high charge transfer efficiency of 89%, ON/OFF current ratio of 10⁴, and extremely low programming time of 5 ms can be achieved. This solution‐processable and fast photo‐programmable non‐volatile flash photomemory can trigger the practical application on Li‐Fi.     

Generation of Compositional‐Gradient Structures in Biodegradable,Immiscible, Polymer Blends by Intermolecular Hydrogen‐Bonding Interactions

A biodegradable, immiscible poly(butylenes adipate‐co‐butylenes terephthalate) [P(BA‐co‐BT)]/poly(ethylene oxide) (PEO) polymer blend film with compositional gradient in the film‐thickness direction has been successfully prepared in the presence of a low‐molecular‐weight compound 4,4′‐thiodiphenal (TDP), which is used as a miscibility‐enhancing agent. The miscibilities of the P(BA‐co‐BT)/PEO/TDP ternary blend films and the P(BA‐co‐BT)/PEO/TDP gradient film were investigated by differential scanning calorimetry (DSC). The compositional gradient structure of the P(BA‐co‐BT)/PEO/TDP (46/46/8 w/w/w) film has been confirmed by microscopic mapping measurement of Fourier‐transform infrared spectra and dynamic mechanical thermal analysis. We have developed a new strategy for generating gradient‐phase structures in immiscible polymer‐blend systems by homogenization, i.e., adding a third agent that can enhance the miscibility of the two immiscible polymers through simultaneous formation of hydrogen bonds with two component polymers.     

Preparation of Tortuous 3D γ‐CsPbI3 Films at Low Temperature by CaI2 as Dopant for Highly Efficient Perovskite Solar Cells

Inorganic cubic CsPbI₃ perovskite (α‐CsPbI₃) has been widely explored for perovskite solar cells (PSCs) due to its thermal stability and suitable bandgap of 1.73 eV. However, α‐CsPbI₃ usually requires high synthesis temperatures (>320 °C). Additionally, it usually undergoes phase transition to the nonperovskite structure phase (β‐CsPbI₃), which results in poor photoelectric performance in devices. In this study, it is first found that the tortuous 3D CsPbI₃ phase (γ‐CsPbI₃) can be prepared and used for PSCs by solution process without any additive at low temperature (60 °C). The γ‐CsPbI₃ exhibits suitable bandgap of 1.75 eV and favorable photoelectric properties. However, γ‐CsPbI₃ is a metastable phase and easily transforms into β‐CsPbI₃ in ambient moisture. In order to improve the stability of γ‐CsPbI₃, calcium ions (Ca²⁺) with a relatively small radius of 100 pm are used to partially substitute lead ions (119 pm). This research proves that Ca²⁺ can effectively improve the stability of the γ‐CsPbI₃ at room temperature. By optimizing the doping concentration of Ca²⁺ (CsPb_1?xCa_xI₃, x is from 0% to 2%), the Ca²⁺‐doped γ‐CsPbI₃ PSCs achieve a hysteresis‐free J–V curve and a maximum power conversion efficiency (PCE) of 9.20%.     

Controlled n‐Doping in Air‐Stable CsPbI2Br Perovskite Solar Cells with a Record Efficiency of 16.79%

Cesium‐based inorganic perovskites, such as CsPbI₂Br, are promising candidates for photovoltaic applications owing to their exceptional optoelectronic properties and outstanding thermal stability. However, the power conversion efficiency of CsPbI₂Br perovskite solar cells (PSCs) is still lower than those of hybrid PSCs and inorganic CsPbI₃ PSCs. In this work, passivation and n‐type doping by adding CaCl₂ to CsPbI₂Br is demonstrated. The crystallinity of the CsPbI₂Br perovskite film is enhanced, and the trap density is suppressed after adding CaCl₂. In addition, the Fermi level of the CsPbI₂Br is changed by the added CaCl₂ to show heavy n‐type doping. As a result, the optimized CsPbI₂Br PSC shows a highest open circuit voltage of 1.32 V and a record efficiency of 16.79%. Meanwhile, high air stability is demonstrated for a CsPbI₂Br PSC with 90% of the initial efficiency remaining after more than 1000 h aging in air.     

Improved Performance and Stability of All‐Inorganic Perovskite Light‐Emitting Diodes by Antisolvent Vapor Treatment

All‐inorganic perovskite light‐emitting diodes (LEDs) reveal efficient luminescence with high color purity, but their modest brightness and poor stability are still critical drawbacks. Here, the luminescent efficiency and the stability of perovskite LEDs (PeLEDs) are boosted by antisolvent vapor treatment of CsPbBr₃ embedded in a dielectric polymer matrix of polyethylene oxide (PEO). A unique method is developed to obtain high quality CsPbBr₃ emitting layers with low defects by controlling their grain sizes. CsPbBr₃ in PEO matrix is post‐treated with antisolvent of chloroform (CF), leading to microcrystals with a size of ≈5 µm along the in‐plane direction with active emitting composite of 90%. A device based on CF post‐treatment (CsPbBr₃‐PEO‐CF) film displays a brightness of up to 51890 cd m^?2 with an external quantum efficiency of 4.76%. CsPbBr₃‐PEO‐CF PeLED still maintains 82% of its initial efficiency after 80 h continuous operation in ambient air, which indicates relatively good device stability. This work highlights that film quality is not only key to promoting fluorescence in CsPbBr₃, but also to achieving higher performance PeLEDs.     

Composition Engineering of All‐Inorganic Perovskite Film for Efficient and Operationally Stable Solar Cells

Cesium‐based inorganic perovskites have recently attracted great research focus due to their excellent optoelectronic properties and thermal stability. However, the operational instability of all‐inorganic perovskites is still a main hindrance for the commercialization. Herein, a facile approach is reported to simultaneously enhance both the efficiency and long‐term stability for all‐inorganic CsPbI_2.5Br_0.5 perovskite solar cells via inducing excess lead iodide (PbI₂) into the precursors. Comprehensive film and device characterizations are conducted to study the influences of excess PbI₂ on the crystal quality, passivation effect, charge dynamics, and photovoltaic performance. It is found that excess PbI₂ improves the crystallization process, producing high‐quality CsPbI_2.5Br_0.5 films with enlarged grain sizes, enhanced crystal orientation, and unchanged phase composition. The residual PbI₂ at the grain boundaries also provides a passivation effect, which improves the optoelectronic properties and charge collection property in optimized devices, leading to a power conversion efficiency up to 17.1% with a high open‐circuit voltage of 1.25 V. More importantly, a remarkable long‐term operational stability is also achieved for the optimized CsPbI_2.5Br_0.5 solar cells, with less than 24% degradation drop at the maximum power point under continuous illumination for 420 h.     

A Hybrid Poly(ethylene oxide)/ Poly(vinylidene fluoride)/TiO2 Nanoparticle Solid‐State Redox Electrolyte for Dye‐Sensitized Nanocrystalline Solar Cells

High‐efficiency all‐solid‐state dye‐sensitized nanocrystalline solar cells have been fabricated using a poly(ethylene oxide)/poly(vinylidene fluoride) (PEO/PVDF)/TiO₂‐nanoparticle polymer redox electrolyte, which yields an overall energy‐conversion efficiency of about 4.8 % under irradiation by white light (65.2 mW cm^–2). The introduction of PVDF (which contains the highly electronegative element fluorine) and TiO₂ nanoparticles into the PEO electrolyte increases the ionic conductivity (by about two orders of magnitude) and effectively reduces the recombination rate at the interface of the TiO₂ and the solid‐state electrolyte, thus enhancing the performance of the solar cell.     

Passivated Perovskite Crystallization via g‐C3N4 for High‐Performance Solar Cells

Organometallic halide perovskite films with good surface morphology and large grain size are desirable for obtaining high‐performance photovoltaic devices. However, defects and related trap sites are generated inevitably at grain boundaries and on surfaces of solution‐processed polycrystalline perovskite films. Seeking facial and efficient methods to passivate the perovskite film for minimizing defect density is necessary for further improving the photovoltaic performance. Here, a convenient strategy is developed to improve perovskite crystallization by incorporating a 2D polymeric material of graphitic carbon nitride (g‐C₃N₄) into the perovskite layer. The addition of g‐C₃N₄ results in improved crystalline quality of perovskite film with large grain size by retarding the crystallization rate, and reduced intrinsic defect density by passivating charge recombination centers around the grain boundaries. In addition, g‐C₃N₄ doping increases the film conductivity of perovskite layer, which is beneficial for charge transport in perovskite light‐absorption layer. Consequently, a champion device with a maximum power conversion efficiency of 19.49% is approached owing to a remarkable improvement in fill factor from 0.65 to 0.74. This finding demonstrates a simple method to passivate the perovskite film by controlling the crystallization and reducing the defect density.     

A Dual‐Retarded Reaction Processed Mixed‐Cation Perovskite Layer for High‐Efficiency Solar Cells

Mixed‐cation perovskite solar cells (PSCs) have become of enormous interest because of their excellent efficiency, which is now crossing 23.7%. Their broader absorption, relatively high stability with low fabrication cost compared to conventional single phase ABX₃ perovskites (where A: organic cation; B: divalent metal ion; and X: halide anion) are key properties of mixed‐halide mixed‐cation perovskites. However, the controlling reaction rate and formation of extremely dense, textured, smooth, and large grains of perovskite layer is a crucial task in order to achieve highly efficient PSCs. Herein, a new simple dual‐retarded reaction processing (DRP) method is developed to synthesize a high‐quality mixed‐cation (FAPbI₃)_0.85(MAPbBr₃)_0.15 (where MAPbBr₃ stands for methylammonium lead bromide and FAPbI₃ stands for formamidinium lead iodide) perovskite thin film via intermediate phase and incorporation of nitrogen‐doped reduced graphene oxide (N‐rGO). The reaction rate is retarded via two steps: first the formation of intermediate phase and second the interaction of the nitrogen groups on N‐rGO with hydrogen atoms from formamidinium cations. This DRP process allows for the fabrication of PSCs with maximum conversion efficiency higher than 20.3%.     

Electron‐Transport‐Layer‐Assisted Crystallization of Perovskite Films for High‐Efficiency Planar Heterojunction Solar Cells

Crystal engineering of CH₃NH₃PbI₃ perovskite materials through template‐directed nucleation and growth on PbI₂ nuclei dispersed in a polar fullerene (C₆₀ pyrrolidine tris‐acid, CPTA) electron transport layer (ETL) (CPTA:PbI₂) is proposed as a route for controlling crystallization kinetics and grain sizes. Chemical analysis of the CPTA:PbI₂ template confirms that CPTA carboxylic acid groups can form a monodentate or bidentate chelate with Pb(II), resulting in a lower nucleation barrier that promotes rapid formation of the tetragonal perovskite phase. Moreover, it is demonstrated that a uniform CH₃NH₃PbI₃ film with highly crystalline and large domain sizes can be realized by increasing the spacing between nuclei to retard perovskite crystal growth via careful control of the preferred nucleation site distribution in the CPTA:PbI₂ layer. The improved perovskite morphology possesses a long photoluminescence lifetime and efficient photocarrier transport/separation properties to eliminate the hysteresis effect. The corresponding planar heterojunction photovoltaic yields a high power conversion efficiency (PCE) of 20.20%, with a high fill factor (FF) of 81.13%. The average PCE and FF values for 30 devices are 19.03% ± 0.57% and 78.67% ± 2.13%, respectively. The results indicate that this ETL template‐assisted crystallization strategy can be applied to other organometal halide perovskite‐based systems.     

Photoferroelectric Thin Films for Flexible Systems by a Three‐in‐One Solution‐Based Approach

The effective incorporation of (multi)functional oxides into next‐generation flexible electronics systems requires novel fabrication technologies that enable the direct integration of crystalline oxide layers in them. Unfortunately, this is considerably challenging due to the thermal incompatibility between the crystallization temperatures of metal oxides (>600 °C) and the thermal stability of the flexible polymer substrates conventionally used (<400 °C). Here, it is shown that BiFeO₃ thin films can be grown on flexible plastic by solution processing involving three different but complementary strategies to induce the crystallization of the perovskite phase at a lower temperature limit of 325 °C. This “three‐in‐one” approach is based on the synthesis of tailored metal precursors i) with a molecular structure resembling the crystalline structure of the oxide phase, which additionally allows both ii) photochemical and iii) internal combustion reactions taking place in the thin films. The flexible BiFeO₃ thin films obtained from a specifically designed molecular complex with N‐methyldiethanolamine yield a large remnant polarization of 17.5 µC cm^?2, also showing photovoltaic and photocatalytic effects. This result paves the way for the direct integration of an interesting class of oxides with photoferroelectric properties in flexible devices with multiple applications in information and communication technology, and energy.     

Spray‐Coated Colloidal Perovskite Quantum Dot Films for Highly Efficient Solar Cells

A fully automated spray‐coated technology with ultrathin‐film purification is exploited for the commercial large‐scale solution‐based processing of colloidal inorganic perovskite CsPbI₃ quantum dot (QD) films toward solar cells. This process is in the air outside the glove box. To further improve the performance of QD solar cells, the short‐chain ligand of phenyltrimethylammonium bromide (PTABr) with a benzene group is introduced to partially substitute for the original long‐chain ligands of the colloidal QD surface (namely PTABr‐CsPbI₃). This process not only enhances the carrier charge mobility within the QD film due to shortening length between adjacent QDs, but also passivates the halide vacancy defects of QD by Br^? from PTABr. The colloidal QD solar cells show a power conversion efficiency (PCE) of 11.2% with an open voltage of 1.11 V, a short current density of 14.4 mA cm^?2, and a fill factor of 0.70. Due to the hydrophobic surface chemistry of the PTABr–CsPbI₃ film, the solar cell can maintain 80% of the initial PCE in ambient conditions for one month without any encapsulation. Such a low‐cost and efficient spray‐coating technology also offers an avenue to the film fabrication of colloidal nanocrystals for electronic devices.     

Efficient Light‐Emitting Electrochemical Cells (LECs) Based on Ionic Iridium(III) Complexes with 1,3,4‐Oxadiazole Ligands

Eight new iridium(III) complexes 1‐8 , with 1,3,4‐oxadiazole (OXD) derivatives as the cyclometalated C^N ligand and/or the ancillary N^N ligands are synthesized and their electrochemical, photophysical, and solid‐state light‐emitting electrochemical cell (LEC) properties are investigated. Complexes 1 , 2 , 7 and 8 are additionally characterized by single crystal X‐ray diffraction. LECs based on complexes 1‐8 are fabricated with a structure indium tin oxide (ITO)/poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/cationic iridium complex:ionic liquid/Al. LECs of complexes 1 – 6 with OXD derivatives as the cyclometalated ligands and as the ancillary ligand show yellow luminescence (λ_max = 552–564 nm). LECs of complexes 7 and 8 with cyclometalated C^N phenylpyridine ligands and an ancillary N^N OXD ligand show red emission (λ_max 616–624 nm). Using complex 7 external quantum efficiency (EQE) values of >10% are obtained for devices (210 nm emission layer) at 3.5 V. For thinner devices (70 nm) high brightness is achieved: red emission for 7 (8528 cd m^?2 at 10 V) and yellow emission for 1 (3125 cd m^?2 at 14 V).